Jooq Generator: Groovy DSL fields not working

Question

I am using the nu.studer.jooq plugin, jooq version 3.14.15. I am trying to define synthetic primary keys like in the docs: https://www.jooq.org/doc/latest/manual/code-generation/codegen-advanced/codegen-config-database/codegen-database-synthetic-objects/codegen-database-synthetic-pks/

Error I get: Invalid property: 'field' on extension 'jooq.main.generationTool.generator.database.syntheticObjects.primaryKeys.primaryKey', value: COLUMN1. Please check the current XSD: https://www.jooq.org/xsd/jooq-codegen-3.14.0.xsd.

jooq {
version = '3.14.15'
configurations {
    main {
        generationTool {

        }
        generator {
            name = 'org.jooq.codegen.DefaultGenerator'
            database {
                syntheticObjects {
                    primaryKeys {
                        primaryKey {
                            tables = 'my_table'
                            fields {
                                field = 'column1'
                                field = 'column2'
                            }
                        }
                    }
                }
            }
        }
    }
}

}